Combined compensated inhalationexhalation valve for pressure breathing mask



Jan. 21, 1958 H. w. SEELER 2,820,

COMBINED COMPENSATED INHALATION'EXHALATION VALVE FOR PRESSURE BREATHINGMASK Filed Nov. 29, 1955 2 Sheets-Sheet 1 TEE-T5 uvvsNron MFA/RY W 55in? H. w. SEELER 2,820,469 COMBINED COMPENSATED INHALATION-EiG-IALATIONVALVE FOR PRESSURE BREATHING MASK 2 Sheets-Sheet 2 Jan. 21, 1958 FiledNov. 29, 1955 United States COMBINED COMPENSATED INHALATIUN- EXHALATIONVALVE FOR PRESSURE BREATHING MASK Henry W. Seeler, Dayton, Ohio,assignor to the United States of America as represented by the Secretaryof the Air Force The invention described herein may be manufactured andused by or for the United States Government for governmental purposeswithout payment to me of any royalty thereon.

This invention relates to a valve assembly and, more particularly, to apressure compensated inhalation and exhalation valve assembly for ipressure breathing in a high altitude mask.

High altitude pressure breathing masks currently in use have threevalves built into them. This causes the mask to be unnecessarily largeand uncomfortable. The valve assembly in this invention takes over theWork of these valves by compactly combining the functions of aninhalation valve and a pressure compensated exhalation valve. As aresult, breathing masks can be made smaller and lighter. This has animportant effect on the ability of the wearer to use the mask for longperiods of time without discomfort. Accordingly, a principal feature ofthis inventionis to provide a valve assembly for a breathing mask thatcombines the functions of an inhalation valve andpressure compensatedexhalation valve.

An additional object of this invention is to provide a compact andefficient means for completely pressure compensating the exhalationportion of the vah'e assembly in all pressure ranges.

A further object of this invention is to provide a valve assemblydesigned so the low temperature oxygen supplied to the valve assemblycannot freeze the exhalation moisture in the valve assembly and causethe exhalation valve to become frozen.

Still another object of this invention is to provide a valve assemblyhaving means for preventing a low pressure drop in the oxygen supplyconduit from causing the exhalation valve to open due to the pressuredrop.

These and other objects of this invention will become more apparent whenread in the light of the accompanying drawings and specification whereinthe scope of this invention is defined by reference to the appendedclaims wherein:

Fig. 1 is a side elevation of the valve assembly disclosing the annularport and showing the mask receiving groove and the oxygen hose receivingstern portion.

Fig. 2 is an end view of the valve assembly disclosing the annular body.

Fig. 3 is a section taken on line 3-4: of Fig. 2.

Fig. 4 is a detail of the valve assembly disclosing the way theexhalation valve is pressure compensated at various pressures.

Fig. 5 is a sectional view of a modified form of a valve assembly anddiscloses in particular an additional method of preventing a lowpressure drop in an oxygen supply conduit from causing the exhalationvalve to open due to that pressure drop.

Fig. 6 is an enlarged detail fragmentary sectional view of a portion ofa modified valve assembly of 'Fig. 5.

I Fig. 7'is a horizontal sectional view through the tubular exhalationvalve support.

Referring to thedrawings by reference numerals and atent ice moreparticularly to Fig. 3, the compensated inhalation and exhalation valveassembly indicated generally at It comprises an annular tubular housing12 having an inner end 13 and an outer end 15 (see Figs. 1 and 2). Thehousing has a tubular stem portion or conduit to adapted to be securedto an oxygen supply hose and an annular mask receiving groove 16 adaptedto be inserted in a hole prepared in an oxygen mask. An inhalationchamber 18 and an exhalation chamber 20 in the housing 12 are separatedby a movable dividing wall 22 so that the exhalation chamber is at theinner end of the housing 12 and the inhalation chamber is near the outerend. This dividing wall consists of an annular inhalation valve 26 andan annular exhalation valve 24. Valve 24 includes a rigid tubularsupport portion 21 and a diaphragm 38. The inhalation valve is anannular resilient flexible disc or diaphragm having a centrally disposedaxially extending boss portion 28. This boss portion 28 is inserted in ahole 30 in the inhalation cross support member or spider 32. This crosssupport member is mounted on the inner end 33 of the rigid tubularsupport portion 21 of the exhalation valve. The periphery of theinhalation valve 26 is adapted to make a one-way sealing contact withthe valve seat 34 on the edge of the exhalation valve portion 21 andclose oil the port 17 connecting the inhalation and exhalation chambers.As seen in Fig. 3, the inhalation valve opens whenever the pressure inthe inhalation chamber exceeds pressures in the exhalation chamber. Thisequalizes the gas pressures in both chambers. The exhalation valve 24makes a sealing contact with valve seat 25 annularly disposed on body 12of. the valve assembly. The exhalation chamber 2% communicates with theambient air through ports 36 which are opened and closed by theexhalation valve 24. On the opposite end of the exhalation valve portion21, an annular ring-shaped diaphragm 38is mounted. One edge of thisdiaphragm is secured to the housing 12 and the other edge is secured toend 35 of the rigid tubular portion 21. The diaphragm is semicircular incross section in planes perpendicular to the plane of the diaphragm andtransverse to its periphery for purposes described below.

An additional cross support member or bridge 37 is mounted in a supportmember receiving groove 40 in the body of the housing. This crosssupport member 37 has upstanding projections 42 adapted to maintainlight coil spring 44 in position in the housing. Coil spring 44 bearsagainst cross support member 37 at one end and the cross support memberor spider 32 at the other end which is mounted on exhalation valve 24.The spring i has the effect of biasing the exhalation valve 24 into aclosed position. An additional cross support member or spider do ismounted in the inner end 47 of tubular stem member 14. This supportmember 46 has a centrally disposed hole 48 adapted to receive thecentrally disposed boss 5% of an annular flexible diaphragm inlet valvemember 52. This valve member 52 offers little resistance to incominggases but if the pressure in the oxygen supply hose should drop to avalue lower than the pressure of a gas in the exhalation chamber 18,this valve closes making a sealing contact with valve seat 49 on theperiphery of the cross support member 46, closing ofi the communicationbetween the inhalation chamber and the tubular supply member 14. Thisprevents a drop in pressure in the oxygen supply from opening theexhalation or exhaust valve 24. If this valve were omitted, it can beseen that pressure fluctuations in the oxygen supply conduit would causethe exhalation valve to fluctuate between open and closed positions.

The important feature of this invention lies in the way the valveassembly is always completely pressure compensated throughcut allpressure ranges. As seen in Fig. 4-,

the exhalation valve has a surface 27 in the exhalation chamber and asurface 29 in the inhalation chamber. The force F acting on theexhalation valve due to the pressure P in the exhalation chamber is theproduct of the pressure P multiplied by the projection of the area ofthe surface 27 on a plane transverse to the direction of motion of theexhalation valve. This area is referred to in this application as theeffective area of the exhalation valve in the exhalation chamber. Inthis case the projection of surface 27 in the exhalation chamber wouldbe circle of diameter D, therefore, the force acting on the exhalationvalve due to the pressure in the exhalation chamber is P multiplied byIn order to completely pressure compensate the exhalation valve, thisforce must be opposed by an identical force acting in the oppositedirection. Since the gas pressure in both chambers is the same, itfollows that the effective areas of the surfaces of the exhalation valvein both chambers must also be the same to balance these pressure forces.This has been accomplished through the use of the ring-shaped diaphragm38. It has been found that the elfective area of the surface of theexhalation valve in the inhalation chamber can be determined bymeasuring the circular area surrounded by the apex 39 of thesemicircular crosssection of the ring-shaped diaphragm. If the diameterof the apex circle is D, the effective area is Increasing the internalpressure from P to values P or P displaces the ring-shaped diaphragm tothe positions indicated by the dotted lines, see Fig. 4. It can be seen,however, that though the cross-sectional configuration of thering-shaped diaphragm has been altered, the apex diameter distance hasnot been changed. This apex diameter is made exactly equal to thediameter of the projection of surface 27 in the exhalation chamber. As aresult, the pressure forces acting on the exhalation valve arecompletely balanced in all pressure ranges and the only force necessaryto be overcome by exhalation pressure is a slight biasing force on theexhalation valve exerted by spring 44. In other words, this structurekeeps exhalation pressure necessary to open the exhalation valve againstthe force of the biasing spring independent of the gas pressure enteringthe valve assembly. The result is that with this method of completepressure compensation, the bias on spring 44 can be very weak. Thismakes possible a high altitude breathing mask which can be used for longperiods without noticeable exertion. In the example disclosed in thiscase, the exhalation valve was annular and the diaphragm ring shaped.This appears to be the preferable form, but it is within thecontemplation of this invention to use other shapes as may be required.For example, the exhalation valve could be oval or square. It is onlynecessary that the diaphragm be semicircular in cross-section and haveone edge secured to the periphery of the valve and the other secureddirectly to the housing to completely pressure compensate the exhalationvalve.

Another extremely important feature of this valve assembly is the radialand axial separation of the inhalation valve 26 from the exhalationvalve 24. At very high altitudes, pressurized oxygen entering the maskhas a very low temperature. This very cold gas mixes with the moisturefrom the breath in the exhalation chamber and freezes it. In theseparation were not maintained between the inhalation and exhalationvalve, the frozen exhalation moisture would freeze the exhalation valvemaking it inoperative. As seen in Fig. 3, the inhalation valve 26 ismounted 31 closer to the inner end 13 of the hous ing 3.2 than theexhalation valve 24, where the housing has an internal diameter of andwhere the internal and external diameters of the tubular portion 21 ofthe exhalation valve at that point are and respectively. Thisdisplacement has been found sufiicient to conduct the cold incominggases away from the warm exhalation moisture adjacent the exhalationvalve 24, and prevents the moisture from freezing the exhalation valvethroughout all temperature ranges reasonably expected to be encountered. Naturally, the required separation of the inhalation valveand exhalation valve will vary in accordance with the size of the valve.

The modified form of the valve assembly disclosed in Fig. 5 is providedto overcome a possible disadvantage caused by mounting valve 52 at theinner end of the tubular stem or conduit portion 14. As can be seen byreference to Fig. 3, the inhalation chamber 18 is completely sealedbetween valves 26 and 52, and since the exhalation valve 24 is connectedto the valve assembly housing by means of a resilient diaphragm 38,exhalation into the valve assembly decreases the separation betweenvalves 26 and 52 and the volume in the inhalation chamber 18. Thisdecrease in the volume in the inhalation chamber produces an increase inthe air pressure in the valve assembly and causes an increase in theforce needed to move the exhalation valve 24 out of engagement withvalve seat 25 during exhalation. To eliminate this increase inexhalation valve resistance, the modified valve assembly shown in Fig. 5has been devised.

This modified valve assembly as shown in Figs. 5 to 7 operates in thesame way as the valve assembly of Fig. 3 with the exception of the meansfor preventing a pressure drop in the oxygen supply hose or conduit fromopening the exhalation valve. As seen in Figs. 5 and 6, the modifiedvalve assembly includes an exhalation valve having a rigid tubularexhalation valve support 60. This valve support has an integral annularsupport flange 62 projecting at right angles to the axis of the rigidtubular valve support 60. Uniformly disposed around the periphery of theannular support flange 62 are a plurality of identical upstandingfingers 64, see Fig. 7. These fingers are disnosed perpendicularly tothe plane of the annular support flange. An annular coil spring 66 ismounted on the support flange 62 and is held in place by fingers 64, asshown in Figs. 5 and 7. A flat ring shaped valve plate 70 concentricwith and reciprocably mounted on valve support 60 rests on coil spring66. A light coil spring 44, stronger than the coil spring 66, has oneend in contact with a ledge 71 on the body 12' and another end incontact with a cross support member or spider 33 on the exhalation valvesupport 60. This coil spring 44 forces valve plate 70 against valve seat25' on valve body 12' and also forces the valve plate 70 in abuttingrelationship with the top edges of fingers 64. The inner edge of annularvalve plate has a downwardly depending U- shaped flange 74, see Fig. 6.One edge of a ring shaped sealing diaphragm 72 is mounted in flange 74while another edge of the diaphragm 72 is mounted in a recess 76 in thesupport member 60, for purposes to be described below.

In operation, a normal exhalation into the valve assembly exerts a forceon the inner surface 27' of the exhalation valve in the exhalationchamber. A portion of this force is exerted on the ring shapedexhalation valve plate 70 and this portion is directly transmittedthrough the abutting contact between valve plate 70 and the upstandingfingers 64, back to the tubular support portion 60, causing the entireexhalation valve to move just as if the ring shaped exhalation valveportion 70 were integral with the tubular support portion 60. So innormal operation the modified form of the exhalation valve assemblybehaves exactly as the valve assembly in Fig. 3.

In the event a pressure drop occurs in the oxygen supply hose or conduit14', the rigid tubular portion 60 of the exhalation valve will move awayfrom valve seats 25. If the ring shaped valve plate 70 were integralwith the rigid tubular portion 60, the exhalation valve would then thebias supplied by the second coil-spring .66 to the: ring shaped valveplate 70. With this arrangemenhas the tubular support 60 movesdownwardly, the coil spring 66 maintains the ring shaped valve plate .70in engagement with the valve seat 25'. Since the ring-shaped valve plate70 can move with respect to the rigid tubular support member 6%, asealing diaphragm must be connected between the inner end of the ringshaped valve plate 70 and the rigid tubular support member 60 to preventleakage between the exhalation chamber and the 'port 36, see Fig. 6.This sealing diaphragm is flexible and U- shaped in cross section topermit the ring shaped diaphragm 70 to move sufficiently far withrespect to the tubular support member 60 so it can be held in sealingengagement with valve seat on body 12 when a drop in pressure in theoxygen supply conduit causes the tubular portion of the exhalation valveto move away from valve seat 25.

Having thus described the invention, what is claimed as new to beobtained by Letters Patent is:

1. A compensated inhalation and exhalation valve assembly for pressurebreathing in a high altitude mask comprising a housing, said housinghaving inhalation and exhalation chambers and a port connecting theexhalation chamber with the ambient air, a dividing wall separating saidinhalation and exhalation chambers, said dividing wall including anexhalation valve operating to open and close said port, biasing meansconnected to said exhalation valve for closing said port, said dividingwall further including means for keeping the exhalation pressurenecessary to open said exhalation valve against the force of saidbiasing means independent of the pressure entering the valve assembly.

2. A compensated inhalation and exhalation valve assembly for pressurebreathing in a high altitude mask comprising a housing, said housinghaving inhalation and exhalation chambers and a port connecting theexhalation chamber with the ambient air, a dividing wall separating saidchambers, said dividing Wall comprising an exhalation valve adapted toopen and close said port, biasing means connected to said exhalationvalve for closing said port, said dividing wall having means forequalizing gas pressures in both chambers during inhalation, saidexhalation valve having opposed surfaces, one surface in each chamber,said exhalation valve including means responsive to gas pressures forcausing the effective area of the surface of the exhalation valve in theexhalation chamber to remain equal to the effective area of the surfaceof the exhalation valve in the inhalation chamber for keeping theexhalation pressure necessary to open said exhalation valve against theforce of said biasing means independent of the gas pressure entering thevalve assembly.

3. A compensated inhalation and exhalation valve assembly for pressurebreathing in a high altitude mask, comprising a housing, said housinghaving inhalation and exhalation chambers and a port connecting theexhalation chamber with the ambient air, means for equalizing gaspressures in both chambers, valve means in the housing separating saidchambers, said valve means including an exhalation valve for opening andclosing said port, biasing means connected to said exhalation valve forclosing said port, said exhalation valve having opposed surfaces, onesurface in each chamber, and including a rigid tubular support portionand a ring shaped diaphragm, said diaphragm semicircular incross-section in planes perpendicular to the plane of the ring shapeddiaphragm and transverse to its periphery, one edge of the diaphragmsecured to the periphery of the tubular portion of the exhalation valveand the other edge secured to the housing, the area of the surface ofthe exhalation valve in the inhalation chamber surrounded by the apexcurve of the cross-section of the diaphragm equal to the effective areaof the surface of the exhalation valve in the exhalation chamber, saiddiaphragm maintaining the effective area of the surface of theexhalation valve in the inhalation chamber equal to the effective areaof the surface of the exhalation valve in the exhalation chamber forkeeping the exhalation pressure necessary to open said exhalation valveagainst the force of said biasing means independent of the pressureentering the valve assembly.

4. A compensated inhalation and exhalation valve assembly for pressurebreathing in a high altitude mask comprising an annular tubular housing,said housing having inhalation and exhalation chambers and a portconnecting the exhalation chamber with the ambient air, a dividing wallin the housing separating said chambers, said dividing wall comprisingan annular exhalation valve for opening and closing said port, biasingmeans connected to said exhalation valve for closing said port, saiddividing wall including means for equalizing gas pressures in bothchambers, said exhalation valve having opposed surfaces, one surface ineach chamber, said exhalation valve including a rigid annular tubularsupport section and a ring-shaped diaphragm, said diaphragm semicircularin cross-section in planes perpendicular to the plane of the ring andtransverse to its periphery, the apex diameter of the surface of thediaphragm in the inhalation chamber equal to the diameter of theeffective area of the surface of the exhalation valve in said exhalationchamber, the outer edge of said diaphragm secured directly to saidhousing, the inner edge secured to the periphery of said rigid annulartubular support portion, said ring-shaped diaphragm maintaining theeffective area of the surface of the exhalation valve in the inhalationchamber equal to the effective area of the surface of the exhalationvalve in the exhalation chamber for keeping the exhalation pressurenecessary to open said exhalation valve against the force of saidbiasing means independent of the gas pressure entering the valveassembly.

5. A compensated inhalation and exhalation valve assembly for pressurebreathing in a high altitude mask comprising a housing, said housinghaving inhalation and exhalation chambers and a first port connectingthe exhalation chamber with the ambient air, a dividing wall in thehousing separating said chambers, said dividing wall including anexhalation valve adapted to open and close said first port, biasingmeans connected to said exhalation valve for closing said port, a secondport in the exhalation valve connecting said inhalation and exhalationchambers, an inhalation valve connected to and movable with saidexhalation valve operating to open and close said second port to admitoxygen to the exhalation chamber, said inhalation valve spaced from saidexhalation valve a distance suflicient to prevent the low temperature ofthe incoming oxygen from freezing exhalation moisture in the vicinity ofthe exhalation valve and causing the exhalation valve to become frozen.

6. The apparatus set forth in claim 5 wherein said inhalation valveopens said second port Whenever the pressure in said inhalation chamberexceeds the pressure in the exhalation chamber and maintains the gaspressure in both chambers substantially equal, said exhalation valvehaving opposed surfaces, one surface in each chamber, said exhalationvalve including means responsive to gas pressures for causing theeffective area of the surface of the exhalation valve in the exhalationchamber to remain equal to the effective area of the surface of theexhalation valve in the inhalation chamber for keeping the exhalationpressure necessary to open said exhalation valve against the force ofsaid biasing means independent of the gas pressure entering the valveassembly.

7. An inhalation and exhalation valve assembly for pressure breathing ina high altitude mask comprising a housing, said housing havinginhalation and exhalation chambers and a port connecting the exhalationchamber with the ambient air, a dividing wall separating said chambers,said dividing Wall including an exhalation valve operating to open andclose said port, an oxygen supply conduit communicating with saidinhalation chamber, said exhalation valve comprising a rigid tubularvalve support, a planar integral support flange extending at rightangles to the axis of said valve support, at least one finger integrallysecured to said support flange and perpendicular thereto, a valve platemovably mounted on said valve support and positioned to abut againstsaid finger, a valve seat on said housing, first biasing means in saidhousing operating on said valve support and forcing said valve plate insealing engagement with said valve seat and in abutting relationshipwith said finger, a second biasing means in said housing operatingbetween said support flange and said valve plate so that if a pressuredrop in said oxygen supply conduit moves said valve support away fromsaid valve seat, said second biasing means will maintain said valveplate in sealing engagement with said valve seat preventing theexhalation valve from opening due to that pressure drop.

Wiggins Oct. 15, 1946 Burns Oct. 28, 1952

